In the poem "To the Nile," what is referred to as the "nurse"? Why?

The poet John Keats is known for many of his "odes," which are types of poems that celebrate or pay homage to their subjects. (For instance, Keats wrote an ode to autumn, an ode to a nightingale, and an ode to a Grecian urn, among others.)

In "To the Nile," Keats takes on the subject of the river Nile, which runs through Egypt and is associated with the great ancient Egyptian civilization. He calls the...

The poet John Keats is known for many of his "odes," which are types of poems that celebrate or pay homage to their subjects. (For instance, Keats wrote an ode to autumn, an ode to a nightingale, and an ode to a Grecian urn, among others.)

In "To the Nile," Keats takes on the subject of the river Nile, which runs through Egypt and is associated with the great ancient Egyptian civilization. He calls the river many things, including the "Chief of the Pyramid and Crocodile!" He also calls the Nile a "nurse": 

"Nurse of swart nations since the world began, Art thou so fruitful? ..." (line 5-6)

Here, Keats' use of the word "nurse" can be a little confusing. He doesn't mean, in this case, a medical nurse, someone who takes care of people who are sick or injured. Instead, Keats is referring to something more like a "wet nurse," which was historically a woman who nursed a baby when it was born in lieu of a mother. In other words, by calling the Nile a "nurse of... nations," Keats is saying that the Nile is what fed and watered civilizations when they were young, enabling them to have the nutrients they needed to grow and mature.